Endocrine Abstracts

Introduction: The incidence, cell origin, histopathologic features and prognosis of papillary and medullary carcinoma are considered to be completely different. Simultaneous occurrence of medullary and papillary thyroid carcinoma in the same patient is rare. Here, we present a patient with synchronous medullary thyroid carcinoma and papillary microcarcinoma occurring in a thyroid with chronic lymphocytic thyroiditis.

Case: A 47 years old woman with no history of chronic illness and no pathologic sign except palpable nodules in thyroid applied with swelling and intermittant pain in the neck. She was euthyroid both clinically and laboratuary. In thyroid ultrasonography, multiple hypoechoic nodules with microcalcifications in left lobe of thyroid were detected. Because, fine needle aspiration biopsy of the 13×10 mm nodule in superior posterior left lobe was reported as suspicious for medullary carcinoma, she underwent bilateral total thyroidectomy and left radical neck dissection. In pathologic examination, in superior part of left lobe a medullary thyroid carcinoma of 15 mm with thyroid capsule infiltration and lymphovascular invasion was found. Tumor cells were strongly positive for calcitonin, chromogranin and carcinoembryonic antigen, immunohistochemically. Additionaly, there was a papillary microcarcinoma foci of 1 mm in lateral part of the same lobe. Three lymph nodes were positive for medullary carcinoma metastases also, and chronic lymphocytic thyroiditis was detected in remaining thyroid tissue. MEN was excluded with laboratory and imaging studies. Postoperative serum calcitonin was <2 pg/ml. She was treated with radioactive iodine.

Conclusion: It is still not obvious whether coexistence of medullary carcinoma and papillary carcinoma in thyroid is just incidental or due to a common stem cell or genetic alteration. Also, role of lymphocytic infiltration in this coexistence remains unidentified. Further investigations and genetic analyses are needed to explain the pathogenesis of simultaneous lymphocytic thyroiditis and papillary and medullary carcinoma in the same thyroid.